Chest
Volume 135, Issue 3, March 2009, Pages 669-677
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Original Research
Critical Care Medicine
Intentional Leaks in Industrial Masks Have a Significant Impact on Efficacy of Bilevel Noninvasive Ventilation: A Bench Test Study

https://doi.org/10.1378/chest.08-1340Get rights and content

Background

During noninvasive ventilation, nonintentional leaks have a detrimental effect on the efficacy of ventilation. A wide range of industrial masks are available, with intentional leaks of different importance. The potential impact of this variability in intentional leaks on performances of bilevel ventilators has not been assessed.

Objective

To measure intentional leaks in seven different industrial masks and determine whether higher leaks modify ventilator performance and quality of ventilation.

Methods

Seven interfaces connected to four ventilators, the VPAP III ST (ResMed; NorthRyde, Australia), the BiPAP Harmony (Respironics; Monroeville, PA), the SmartAir ST (Covidien/Airox; Pau, France), and the GoodKnight 425 ST Bilevel (Covidien/Tyco-Nellcor/Puritan Bennett; Pleasanton, CA), were adapted on a mannequin connected to a lung model (ASL5000, IngMar Medical; Pittsburgh, PA). Inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure were 14 and 4 cm H2O, respectively. The lung model was set with a respiratory rate of 15 cycles per min and a duration of inspiration of 1 s in three simulated conditions (normal, restrictive, and obstructive). Inspiratory trigger delay and effort, capacity to achieve and maintain IPAP, expiratory cycling and tidal volume were analyzed for all masks and ventilators in the three simulated lung conditions.

Results

The level of intentional leaks in the seven masks ranged from 30 to 45 L/min for an IPAP of 14 cm H2O. Importance of leaks did not influence trigger performances. However, capacity to achieve and maintain IPAP was significantly decreased with all ventilators and in all simulated lung conditions when intentional leaks increased. This led to a maximum reduction in delivered tidal volume of 48 mL. Expiratory cycling was not affected by the level of intentional leaks except in obstructive lung conditions.

Conclusion

Mask intentional leaks can impair efficacy of ventilation, especially when > 40 L/min.

Section snippets

Assessment of Intentional Leaks of the Masks

Seven industrial masks were tested: the nasal FlexiFit 405 and the facial FlexiFit 431 (Fischer & Paykel Healthcare; Auckland, New Zealand), the nasal Ultra Mirage and the facial Ultra Mirage (ResMed; NorthRyde, Australia), the nasal ComfortClassic and the facial ComfortFull (Respironics; Monroeville, PA), and the nasal IQ SleepNet (L3-Médical; Vienne, France). The intentional leak valve of each mask was isolated from the mask and adapted on a tight support. This support was connected to a CPAP

Results

Mean ± SD values of TD, trigger PTP, PTP500, Ti-assist, and Vt are given in Table 1, Table 2, Table 3 in normal, restrictive, and obstructive simulated lung mechanics, respectively. ρ values (Spearman rank sum test), listed when significant, quantify for each ventilator the correlation between these parameters and the importance of intentional leaks among the seven tested masks. The relationship for PTP500 and Vt for all four ventilators tested, and relationship between the importance of

Discussion

Nonintentional leaks, occurring during NIV, have a detrimental effect on efficacy of NIV in both acute and chronic conditions.14, 15, 16 To our knowledge, the present study is the first to assess a wide range of masks with different intentional leaks and analyze the consequences of increasing intentional leaks on trigger efficacy, capacity to achieve and maintain preset pressure, and inspiratory/expiratory cycling. Our results can be summarized as follows: (1) within a 30 to 45 L/min range (at

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  • Cited by (0)

    The authors have no conflicts of interest to disclose.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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